Worldwide Prevalence of Anaemia 1993–2005 WHO Global Database on Anaemia
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Worldwide prevalence of anaemia 1993–2005 WHO Global Database on Anaemia Centers for Disease Control and Prevention Atlanta Worldwide prevalence of anaemia 1993–2005 WHO Global Database on Anaemia Editors Bruno de Benoist World Health Organization Geneva, Switzerland Erin McLean World Health Organization Geneva, Switzerland Ines Egli Institute of Food Science and Nutrition, ETH – Zurich, Switzerland Mary Cogswell Centers for Disease Control and Prevention Atlanta, Georgia WHO Library Cataloguing-in-Publication Data Worldwide prevalence of anaemia 1993–2005 : WHO global database on anaemia / Edited by Bruno de Benoist, Erin McLean, Ines Egli and Mary Cogswell. 1.Anemia – prevention and control. 2.Anemia – epidemiology. 3.Prevalence. I.World Health Organization. ISBN 978 92 4 159665 7 (NLM classification: WH 155) © World Health Organization 2008 All rights reserved. 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Cover photographs by Virot Pierre, Armando Waak, Carlos Gaggero Designed by minimum graphics Printed in Spain Contents Preface v Acknowledgements vi Abbreviations vii 1. Introduction 1 1.1 Anaemia: a public health problem 1 1.1.1 Etiology 1 1.1.2 Health consequences 1 1.1.3 Assessing anaemia 1 1.2 Control of anaemia 1 1.2.1 Correcting anaemia 1 2. Methods 3 2.1 Data sources – The WHO Global Database on Anaemia 3 2.2 Selection of survey data 3 2.2.1 Administrative level 3 2.2.2 Population groups 4 2.3 Defining anaemia 4 2.3.1 Haemoglobin threshold 4 2.3.2 Estimated anaemia prevalence for countries with no survey data 5 2.3.3 Uncertainty of estimates 5 2.3.4 Combining national estimates 5 2.3.5 Global anaemia prevalence 5 2.3.6 Classification of anaemia as a problem of public health significance 6 2.4 Population coverage, proportion of population, and the number of individuals with anaemia 6 2.4.1 Population coverage 6 2.4.2 Proportion of population and the number of individuals affected 6 3. Results and Discussion 7 3.1 Results 7 3.1.1. Population coverage 7 3.1.2 Proportion of population and number of individuals with anaemia 7 3.1.3 Classification of countries by degree of public health significance of anaemia 8 3.2 Discussion 8 3.2.1 Population coverage 8 3.2.2 Strengths of estimates 8 3.2.3 Limitations of estimates 8 3.2.4 Proportion of population and the number of individuals with anaemia 12 3.2.5 Classification of countries by degree of public health significance of anaemia, based on haemoglobin concentration 12 3.2.6 Comparison to previous estimates 12 3.3 Conclusion 12 References 14 CONTENTS iii Annexes Annex 1 WHO Member States grouped by WHO and UN regions 15 Table A1.1 WHO Member States grouped by WHO regions 15 Table A1.2 WHO Member States grouped by UN regions and subregions 16 Annex 2 Results by UN region 18 Table A2.1 Population coverage by anaemia prevalence surveys (national or subnational) conducted between 1993 and 2005 by UN region 18 Table A2.2 Anaemia prevalence by UN region 18 Annex 3 National estimates of anaemia 20 Table A3.1 Country estimates of anaemia prevalence in preschool-age children 20 Table A3.2 Country estimates of anaemia prevalence in pregnant women 25 Table A3.3 Country estimates of anaemia prevalence in non-pregnant women of reproductive age 30 Table A3.4 Country references 35 Tables Table 2.1 Haemoglobin thresholds used to define anaemia 4 Table 2.2 Prediction equations used to generate anaemia estimates for countries without survey data 5 Table 2.3 Classification of anaemia as a problem of public health significance 6 Table 3.1 Population coverage (%) by anaemia prevalence surveys (national or subnational) conducted between 1993 and 2005 7 Table 3.2 Global anaemia prevalence and number of individuals affected 7 Table 3.3 Anaemia prevalence and number of individuals affected in preschool-age children, non-pregnant women and pregnant women in each WHO region 8 Table 3.4 Number of countries categorized by public health significance of anaemia 8 Figures Figure 3.1 Anaemia as a public health problem by country (a) Preschool-age children 9 (b) Pregnant women 10 (c) Non-pregnant women of reproductive age 11 iv WORLDWIDE PREVALENCE OF ANAEMIA 1993–2005 Preface Anaemia is a public health problem that affects populations The data available for school-age children, men, and the in both rich and poor countries. Although the primary elderly were not sufficient to generate regional or country- cause is iron deficiency, it is seldom present in isolation. level estimates for these groups, and therefore only global More frequently it coexists with a number of other causes, estimates for these groups are presented. such as malaria, parasitic infection, nutritional deficiencies, In addition, despite the fact that iron deficiency is con- and haemoglobinopathies. sidered to be the primary cause of anaemia, there are few Given the importance of this pathology in the world, nu- data on the prevalence of this deficiency. The likely reason merous countries conduct interventions to reduce anaemia; is that iron assessment is difficult because the available in- particularly in the groups most susceptible to its devastat- dicators of iron status do not provide sufficient information ing effects: pregnant women and young children. In order alone and must be used in combination to obtain reliable to assess the impact of these interventions, the adequacy information on the existence of iron deficiency. Further- of the strategies implemented, and the progress made in more, there is no real consensus on the best combination of the fight against anaemia, information on anaemia preva- indicators to use. Another reason is that the role of factors lence must be collected. This is the primary objective of the other than iron deficiency in the development of anaemia WHO Global Database on Anaemia. However, estimates has been underestimated by public health officials, because of anaemia prevalence by themselves are only useful if they for a long time anaemia has been confused with iron defi- are associated with a picture of the various causal factors ciency anaemia, and this has influenced the development of that contribute to the development of anaemia in specific strategies and programmes designed to control anaemia. settings. Indeed these factors are multiple and complex, and In this report, the prevalence of anaemia is presented by it is critical to collect accurate information about them to country and by WHO regions. Because these prevalence provide the basis for developing the best interventions for data may be used to identify programme needs by other anaemia control. United Nations agencies, we have presented the estimates In the last three decades, there have been various at- classified by United Nations regions in the annexes. In ad- tempts to produce estimates of the prevalence of anaemia dition, one chapter is dedicated to the criteria used to iden- at different levels including at the global level, but until tify, revise, and select the surveys, and the methodology the present time, there has never been a systematic review developed to generate national, regional, and global esti- of all of the data collected and published with the objec- mates. tive of deriving regional and global estimates. The WHO A lesson learned from producing this report is that in Global Database on Anaemia has filled this gap: data from order for the database to reach its full potential, data should 93 countries, representing as much as 76% of the popula- be collected on other vulnerable population groups such as tion in the case of preschool-age children, were analysed the elderly and school-age children, and surveys should be and used to develop statistical models to generate national more inclusive and collect information on iron status and prevalence estimates for countries with no data within the other causes of anaemia. time frame specified. This report is written for public health officials, nutri- It is surprising that given the public health importance tionists, and researchers. We hope that readers find it useful of anaemia, there are numerous countries lacking national and feel free to share any comments with us.